There were some cat-and-mouse standoffs between protesters and police in Tung Chung as night fell on Saturday

Hong Kong police checked people travelling to the airport for passports and air tickets on Saturday, preventing protesters gathering for another “stress test” of road and rail links in the Chinese-ruled city.

The increased scrutiny was aimed at avoiding the chaos of last weekend, when protesters blocked airport approach roads, threw debris on to train tracks and trashed the MTR subway station in the nearby new town of Tung Chung.

Protesters also occupied the arrivals hall last month, halting and delaying flights, amid a series of clashes with police.

There were some cat-and-mouse standoffs between protesters and police in Tung Chung as night fell on Saturday, but no sign of a return to violence.

Three months of protests have at times paralysed parts of the city, a major Asian financial hub, amid running street battles between protesters and police who have responded with tear gas, pepper spray and water cannon. Violent arrests of protesters have drawn international attention.

Police on Saturday searched bags of people on buses and trains headed to the airport where police and press outnumbered passengers.

There were shouting matches outside the airport between police and people who wanted to pick up arriving family members but were told to go away.

“It’s absolutely ridiculous. We have our 80-year-old relative coming off the flight. How will she get home without our help?” said Donny, only giving his first name. “These police don’t listen to anything we have to say. We are normal people.”

Metro stations attacked

Chek Lap Kok airport was built in the dying days of British rule on reclaimed land around a tiny island and is reached by a series of bridges.

Hundreds of demonstrators, many masked and dressed in black, attacked MTR metro stations on the Kowloon peninsula on Friday night, targeted because of televised scenes of police beating protesters on a metro train on Aug. 31 as they cowered on the floor.

Activists, angry that the MTR closed stations to stop protesters from gathering and demanding CCTV footage of the beatings, tore down signs, broke turnstiles, set fires on the street and daubed graffiti on the walls.

The protests have presented Chinese President Xi Jinping with his greatest popular challenge since he came to power in 2012.

Hong Kong leader Carrie Lam announced concessions this week to try to end the protests, including formally scrapping a hugely unpopular extradition bill, but many said they were too little, too late. She said Beijing backed her “all the way”.

The bill would have allowed extraditions of people to mainland China to stand trial in courts controlled by the Communist Party. In contrast, Hong Kong has an independent judiciary dating back to British rule.

But the demonstrations, which began in June, have long since broadened into calls for more democracy and many protesters have pledged to fight on.

Hong Kong returned to China in 1997 under a “one country, two systems” formula that guarantees freedoms not enjoyed on the mainland. Many Hong Kong residents fear Beijing is eroding that autonomy.

China denies the accusation of meddling and says Hong Kong is its internal affair. It has denounced the protests, accusing the United States and Britain of fomenting unrest, and warned of the damage to the economy.

The U.S. State Department updated its travel advisory for Hong Kong, warning that U.S. citizens and consular employees had been the targets of a recent propaganda campaign by China “falsely accusing the United States of fomenting unrest”.

The overall risk level remains at the second lowest of a four-level gauge, after it was raised on Aug. 7 to reflect the escalating violence.